Differential or balance mechanism



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R. J. lFlELD DIFFERENTIAL OR BALANCE MECHANISM Filed Feb". 15, 1937 ingz .mv/IX 3 sheets-sheet V1 June 28, 1.9381.

R'. J. IFIELD DIFFERENTIAL 0R BALANCE MECHANISM `Filed Feb. 15,' I195'?3 Sheets-Sheet 2 V .21* J J F1g.2. Tf'

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DIFFERENTIAL OR BALANCE MECHANISM A Filed Feb. 15, 1937 s sheets-sheet 3Figil 13b 27 11 13a v l 12 Patented June 2s, 1938 oFFl CE:`

DIFFERENTIAL -oa BALANCE; MncnANIsM v v Richard Joseph AIiield,4Covent'ry,England.

' Application February 15, 1937 ,1Serial-No. 125,902

' InGreat-Britain Februaryfli, 1936 .Q5 claims'.- (01.5145311555 y-(Granted under the provisions oifsec. '14,

This invention relates to diilerential mecha-` nism: havingI one drivingelement `and two.` co-fV axial driven yelementsveither or both ofWhich-- may be an `internally-toothed annulus or a sun gear, or onemaybe a planet-,carrier-a-nd Vpar-` ticularly to a differential gearsuchas is usedin the drive to the driven road wheels -of motor-l Vvehicles.

`If "one road wheel strikes abump when thel 10;; vehicle is being drivenitis caused to spin under the` driving torque whilst itis oi the ground.

v This results in loss of tractive effort and in tire wear when thewheel again touches-the ground. In a similar manner serious diiiicultiesare some- 15g times encountered when .one wheel lslips on an icy surfaceor in lbogey ground.

It is my main object to avoid these disadvan tages. f y According tod-riven coaxialgear wheels or other elements ,of la differentialmechanism lfrom being driven at such different speeds that the ratio ofthe greater to the less will exceeda predetermined value, ldezsependentupon the maximum differential effect required, vsuch means including an.additionalelement for each coaxial driven element reversely gearedthereto and associated with a .one-way locking device. The one-waylocking devices aayfree-wheel to allow of the driven coaxial elements fbeing driven at the same speed, but they canlock `automatically when thecoaxial elements are driven at dierent speeds to prevent the ratiooi.

thegreater speed to the less speed from exceed- 3:5# ing Athepredetermined'value. u

`In one arrangement according to the,y invention, the lplanet element ofa differential gear` (whether in the form of a bevel gear or of a pair.

50f vehicle is, of course, dependent upon the turn-v.

ing circle of the outer vehicle wheels, the track,

and the wheel base. Thus, in the case of ka mo-k tor-vehicle having atrack of, say 4 feet anda rear Wheel outer turning circle of, say, 30feet,

r5s; the turning circle yfor the inside rear wheel is v the mainieatureof the invention,A mprprovide kmeans for positively. preventingthe22eet, gi-vinga ratio of 30 to 22 or 1-154 to -846 for`one,revolution.of thev driving element. The mechanism shouldbe suchthat the ratio between the,speed'sof, the faster-moving driven coaxialwheel ,-to'the slowerfmovi-ng one will be nearly equal-to but not.' lessthan this ratio. Y

Inthe accompanying diagrammatic drawings (in which like referencecharacters are used to denoteirsixnilar parts/as far as possible)='Figure 1 is a sectional elevation of a common form of differentialgearing adapted according to the'invention, andy Figures 2 to 6 aresimilar viewsato smaller scales, showing other forms of d-iierentlal,gearing when adaptedaccording to the'invention. f. 'Ihereare othersuitable waysv in whichthegears may be arranged to achieve the effect.of restriction bvv reversely gearing the reaction members :to thecoaxial driven gears as will be readily conceived.

In v'the"construction,.of Figure 1, as applied to a differential gear,of. a motor-vehicle, having a crown wheelI Iy fast on acarrier I2 for apair of planet-elements I3,v I3, the carrier being adapted iniknownmanner to enclose the planet elementsv and being, for example,journalled in anti-friction` bearings I4 in a stationary support I5, theplanet elements are bevel pinions meshing with the ldriven elements I6,I6 in the form of sun gears-.,:fast-on the driven half-axles I1, I1. Theplanetl pinions" are also formed with other coaxial ygear teethIS, I8 inmesh with bevel sun gearsv I3, I9 fast onsleeves 20, 20 which are freelymounted ,on the half-axles and connected to the stationary supportthrough one-way locking devices 2I, 2|. Different kinds of one-waylocking, ldevices. vare -well known in practice, though here they areshown in the form of rollertype. fires-wheels, y

/Ifthe drive ratio of each planet pinion I3 to onev of the drivenelements I 6 be, say, 1 to 2, andif the drive ratio of the additionalgearing '(,I 8, I9) be,` say, 2 to-l, then the maximum speed differencewhich can be obtained on the driven half-axles IT will be inthe ratio of11A; to .-"AL,l i.,e., 5,1103 or 15 to 9. (This is a greater ratio, itshould be observed, than is necessary in the case of a motor-vehiclehaving a 4-foot track anda30 foot outer turning circle.)

By-varying the gear ratios aforesaid any desiredmaximum ratio betweenthe speeds of the driven half-axles can be obtained, dependent upontheouter turning clrcle of the vehicle andthe tracl thereof.

In the construction of Figure 2 the differential gearing isz-of the typeWhere `each planet element l of teeth.)

comprises a pair of similar pinions |3a, |3b mounted on parallel shaftsand meshing with one another, each pinion meshing with only one of thedriven coaxial wheels I6, I6. The pinicns are fast, respectively, withgears 22, 22 driving on to .sun gears 23, A23 faston the sleeves 2D, 2liabove referred tor-i. e., the sleeves .which are freely journalled onthe driven half-axles and connected to the stationary support I5 throughthe one-way locking devices 2|, 2|.

In either of the above forms of diiferential gearing, when a closerratio is desired than can conveniently be directly obtained in themanner described, the additional gearing aforesaid may include aplanetary or other form ,of gearing.

Thus, as shown by Figure 3, the driven sun gears i6, i6 of adiiferential gear, in addition to'being fast on the driven half-axles|,V arefast with internally-toothed annuli 24, 21|. intermeshed. withthe sun gears 23, 23 fast on the sleeves 20, 20, by planet elements 25,25 mounted on the planetcarrier `l2 of the differential gear, no matterwhat form the planet elements of the latter take. The planetary gearingsy 23, 24, 25 (by which `the .driven sun gears I6 are connected to theone-4 way locking devices 2|) are designed to give a ratio close to thatwhich is theoretically desired.

In the differential gearing of Figure 4 thev driven coaxial wheels Ia,|612, fast on the halfaxles Il, ll are internally-toothed annuli, eachplanet element comprising a pair of planet pinions |3a, |3112 as abovedescribed. (Although of different diameters, these have the same numberThe planet pinions are meshed, respectively, with sun gears 26,' 26 faston the sleeves 26a, 2619 coacting at 2|, 2| With the oneway lockingdevices (which are actually omitted in this ligure). These locking.devices may include a common outer member.

In the construction of Figure 5` the driven coaxial gears la, I6 are aninternally-toothed annulus Aand a sun, respectively, intermeshed by aplanet-element in the form of a compound pinion 27|.` The larger gearthereof drives the sleeves 20a and also meshes with the smaller gear ofthe compound planet 28 the larger gear whereof drives the sleeve 20D. y

- In the construction of Figure 6 the crown wheel is fast with aninternally-toothed annulus 29 driving on to the smaller gear of acompound planet 36. This smaller gear meshes with the larger gear of acompound planet 3|. i The larger gear of the planet 36 drives the sleeve26h. The larger gear of the planet 3| drives the sleeve 20a, while thesmaller drives thedriven sun gear I6. The planet-carrier 32 is in thiscase fast with one of the half-axles 1.

Such mechanism would not transmit a drive in the reverse direction, andwhen a reverse drive is necessary provision is made for releasing theone-way locking devices orfor reversing them. Free-wheels and the likeare well known in which this is possible. This modification of theoneway locking devices may be effected automatically if desired, eitherby a mechanical connection therewith to the gear change lever, or inother ways. Y

Thus, by means of the invention a differential gear can be constructedto providewhatever differential effect is required and substantially nogreater differential effect, thus reducing the extent to which wheelspin can occur,` and also to provide an automatic sprag eiect by reasonof? the one-way locking devices.v

When used for four, or' more, wheel drives, the

pairs of driving wheels may be differentially coupled and restricted bythis means. For example, When turning a corner the sum of the frontwheel speeds is greater than the sum of the rear wheel speeds, thediierence being dependent on the wheel base of the vehicle. In this casethere is need for only one restricting gear which ma'y'react'throughVthe one-way locking device on to a stationary part to prevent anyexcessive speed of the front wheels and lock to the power member toprevent the speed of the rear wheels from exceeding the front. It willno doublt be appreciated that, when braking, it is impossible for anywheel onwheels to become locked unless they all do.

What I claim as my invention and desire to secure `by Letters Patent ofthe United States isz- 1. A differential gear including a drivingelement, two coaxial driven elements, two additional elements, one-waylocking devices associated with said additional elements, said one-waylocking devices being arranged adjacent one another, and means gearingsaid driven elements to said additional elements such that said drivenelements are prevented from being driven at diierent speeds of which theratio of the greater speed to the less speed exceeds a predeterminedvalue dependent upon the maximum differential eiect required, and saidadditional elements being in the form of sleeves coaxial with saidcoaxial driven elements, one of said sleeves being rotatively fittedupon the other.

2. A differential gear including a driving element, two coaxial drivengear wheels, a planet gear means carried by said driving element andintermeshing said driven gear wheels, one of said driven gear wheelsbeing an internally-toothed annulus, two additional elements in the formof substantially concentric sleeves, and one-way locking devicesassociated with said additional elements and grouped beside one another,said planet gear means being meshed with said additional elements suchthat said driven gear wheels are prevented from being driven atdifferent speeds of which the ratio of the greater speed to the lessspeed exceeds a predetermined value dependent upon the maximumdifferential effect required.

3. A differential gear including a driving element,-two.coaxial drivengear wheels, a planet gear means carried by said driving element andintermeshing said driven gear wheels, both of said driven gear wheelsbeing internally-toothed annuli, two sleeves coaxial with said drivengear wheels, and one-way locking devices associated with said sleeves,said planet gear means being meshed with'said sleeves such that saiddriven gear wheels are prevented from being driven at different speedsof which the ratio of the greater speed to the less speed exceeds apredetermined value dependent upon the maximum differential effectrequired.

4. A differential gear including a driving element, two coaxial drivengear Wheels, a planet gear means carried by said driving element andintermeshing said driven gear wheels, said planet gear means comprisinga pair of intermeshing compound pinions, two substantially concentricsleeves coaxial with said coaxial driven gear wheels, said sleevesformed with gear teeth in mesh, respectively, with said compoundpinions, and one-way locking devices associated with said sleeves andgrouped beside one another, the gearing being such that said driven gearwheels are auf est

prevented from being-driven at different speeds of which'the ratio ofthe greater speed to the llessfspeed exceeds a predetermined valuedependentupon thewmaximum differential effect required. v f

5. A differentialgear Iincluding an internallyvtoothed driving annulus,two coaxial driven elements, a planet gearmeans-intermeshing one of saiddriven elements and said driving annulus,

the otherof said driven elements carrying said.` planet gear means, saidplanet gear means com-l prising a pair of intermeshing compound pinions,and a pair of substantially concentric sleeve elements associated,respectively, with one-Way locking devices, said sleeve elementsmeshing, respectively, with said compound pinions such that said drivenelements are prevented from being driven at different speeds of whichthe ratio of the greater speed to the less speed exceeds aApredetermined value.

RICHARD J. IFIELD.

